N-3 polyunsaturated fatty acid and neuroinflammation in aging and Alzheimer’s disease

Omega-3 fatty acid diglyceride emulsions as a novel injectable acute therapeutic in neonatal hypoxic-ischemic brain injury

Hypoxic-ischemic encephalopathy (HIE), resulting from a lack of blood flow and oxygen before or during newborn delivery, is a leading cause of cerebral palsy and neurological disability in children. Therapeutic hypothermia (TH), the current standard of care in HIE, is only beneficial in 1 of 7-8 cases. Therefore, there is a critical need for more efficient treatments. We have previously reported that omega-3 (n-3) fatty acids (FA) carried by triglyceride (TG) lipid emulsions provide neuroprotection after experimental hypoxic-ischemic (HI) injury in neonatal mice. Herein, we propose a novel acute therapeutic approach using an n-3 diglyceride (DG) lipid emulsions. Importantly, n-3 DG preparations had much smaller particle size compared to commercially available or lab-made n-3 TG emulsions. We showed that n-3 DG molecules have the advantage of incorporating at substantially higher levels than n-3 TG into an in vitro model of phospholipid membranes. We also observed that n-3 DG after parenteral administration in neonatal mice reaches the bloodstream more rapidly than n-3 TG. Using neonatal HI brain injury models in mice and rats, we found that n-3 DG emulsions provide superior neuroprotection than n-3 TG emulsions or TH in decreasing brain infarct size. Additionally, we found that n-3 DGs attenuate microgliosis and astrogliosis. Thus, n-3 DG emulsions are a superior, promising, and novel therapy for treating HIE.

Effect of some local plant extracts on fatty acid composition of fish (Alestes baremoze) during smoking and sun drying in the Far-North region of Cameroon

The objective of this study was to assess the antioxidant activities of three plant extracts (Moringa oleifera leaves, Xylopia aethiopica fruits, and Allium cepa leaves) and to evaluate their effects on the preservation of fish polyunsaturated fatty acids (PUFAs) during smoking and sun-drying processes. PUFAs are highly prone to oxidation during fish processing. The plant extracts were analyzed for their polyphenol contents and were evaluated for their total antiradical capacity. The polyphenol components of each plant were characterized. The hydroethanolic and aqueous extracts were added to the fish at concentrations of 3, 6, 9, and 12 g/L and 10, 20, 30, and 40 g/L, respectively. Butylated hydroxytoluene (BHT) was used as a positive control at a concentration of 2 g/L to compare the antioxidant effects of the plant extracts. The treated fish was subjected to smoking or sun drying and the fatty acid composition of the fish lipid extract was assessed. The results showed that the total polyphenolic, flavonoid, and tannin contents varied significantly from one plant extract to the other (p < .05). The radical scavenging and FRAP increased significantly with the concentration of the plant extracts (p < .05). An HPLC analysis of the extracts led to the preliminary identification of four hydroxycinnamic acids in M. oleifera and X. aethiopica, one anthocyanin and one flavone glycoside in M. oleifera, and four flavan-3-ols in X. aethiopica. Moreover, eight flavonols were preliminarily identified in the three plants. Compared to the control product, these plant extracts significantly protected fish PUFAs from oxidation (p < .05). The aqueous extract of A. cepa at 40 g/L better preserved omega-3 in fish during smoking and sun drying than the control product. Incorporating the three plant extracts during smoking and sun-drying processes can effectively preserve the PUFAs in fish. Therefore, these plants are viable sources of natural antioxidants in the preservation of fish products.

Association of dietary and nutrient patterns with systemic inflammation in community dwelling adults

Purpose

Evidence investigating associations between dietary and nutrient patterns and inflammatory biomarkers is inconsistent and scarce. Therefore, we aimed to determine the association of dietary and nutrient patterns with inflammation.

Methods

Overall, 1,792 participants from the North-West Adelaide Health Study were included in this cross-sectional study. We derived dietary and nutrient patterns from food frequency questionnaire data using principal component analysis. Multivariable ordinal logistic regression determined the association between dietary and nutrient patterns and the grade of inflammation (normal, moderate, and severe) based on C-reactive protein (CRP) values. Subgroup analyses were stratified by gender, obesity and metabolic health status.

Results

In the fully adjusted model, a plant-sourced nutrient pattern (NP) was strongly associated with a lower grade of inflammation in men (OR_Q5vsQ1 = 0.59, 95% CI: 0.38–0.93, p-trend = 0.08), obesity (OR_Q5vsQ1 = 0.43; 95% CI: 0.24–0.77, p-trend = 0.03) and metabolically unhealthy obesity (OR_Q5vsQ1 = 0.24; 95% CI: 0.11–0.52, p-trend = 0.01). A mixed NP was positively associated with higher grade of inflammation (OR_Q5vsQ1 = 1.35; 95% CI: 0.99–1.84, p-trend = 0.03) in all participants. A prudent dietary pattern was inversely associated with a lower grade of inflammation (OR_Q5vsQ1 = 0.72, 95% CI: 0.52–1.01, p-trend = 0.14). In contrast, a western dietary pattern and animal-sourced NP were associated with a higher grade of inflammation in the all participants although BMI attenuated the magnitude of association (OR_Q5vsQ1 = 0.83, 95% CI: 0.55–1.25; and OR_Q5vsQ1 = 0.94, 95% CI: 0.63–1.39, respectively) in the fully adjusted model.

Conclusion

A plant-sourced NP was independently associated with lower inflammation. The association was stronger in men, and those classified as obese and metabolically unhealthy obese. Increasing consumption of plant-based foods may mitigate obesity-induced inflammation and its consequences.

Dietary Intake of n-3 PUFA-Enriched Hen Eggs Changes Inflammatory Markers' Concentration and Treg/Th17 Cells Distribution in Blood of Young Healthy Adults-A Randomised Study

In the present study, we aimed to determine the effects of n-3 polyunsaturated acid (PUFA) supplementation (~1053 mg/per day), i.e., α-linolenic (~230 mg), eicosapentaenoic (~15 mg), and docosahexaenoic acid (~105 mg), through hen eggs, on pro- and anti-inflammatory parameters in healthy individuals (23.8 ± 2.57 years old). Here, we demonstrate differential effects of regular hen eggs (N = 21; W/M = 10/11) and n-3 PUFA-enriched hen eggs (N = 19; W/M = 10/9) consumption on the serum levels of lipid mediators, representation of peripheral T helper cell subsets (recently activated T-helper cells, nTreg, Th17 and non-Th17-IL-17A secreting T-helper lymphocytes) and their functional capacity for cytokine secretion. Both diets significantly altered systemic levels of pro-inflammatory and inflammation resolving lipid mediators; however, only the n-3 PUFAs group showed a significant shift towards anti-inflammatory prostanoids and increased levels of pro-resolving oxylipins. Both study groups showed reduced frequencies of peripheral nTreg lymphocytes and decreased rates of peripheral Th17 cells. Their functional capacity for cytokine secretion was significantly altered only in the n-3 PUFAs group in terms of increased transforming growth factor β-1 and reduced interleukin 6 secretion. Diet supplemented with n-3 PUFAs alters immune response towards inflammation resolving conditions through effects on lipid mediators and cytokine secretion by T lymphocytes in human model without underlying comorbidities.

α-Linolenic acid inhibits Tau aggregation and modulates Tau conformation

Alzheimer's disease is characterized by important patho-proteins, which being composed of Amyloid-β plaques and intracellular neurofibrillary tangles of Tau. Intrinsically disordered protein tau has several interacting partners, which are necessary for its normal functioning. Tau has been shown to interact with various proteins, nucleic acid, and lipids. α-Linolenic acid (ALA) a plant-based omega-3 fatty acid has been studied for its role as neuroprotective and beneficial fatty acid in the brain. In this study, we are focusing on the ability of ALA to induce spontaneous assembly in tau protein. ALA inhibited the Tau aggregation as indicated by reduced ThS fluorescence kinetics, which indicates no aggregation of Tau. Similarly, SDS-PAGE analysis supported that ALA exposure inhibited the aggregation as no higher-order tau species were observed. Along with its ability to impede the aggregation of Tau, ALA also maintains a native random coiled structure, which was estimated by CD spectroscopy. Finally, TEM analysis showed that the formation of Tau fibrils was found to be discouraged by ALA. Hence, conclusion of the study suggested that ALA profoundly inhibited aggregation of Tau and maintained it's the random-coil structure.

Lipid and Lipoprotein Metabolism in Microglia

Microglia, once viewed as static bystanders with limited homeostatic functions, are now considered key players in the development of neuroinflammatory and neurodegenerative diseases. Microglial activation is a salient feature of neuroinflammation involving a dynamic process that generates multitudinous microglial phenotypes that can respond to a variety of situational cues in the central nervous system. Recently, a flurry of single cell RNA-sequencing studies have defined microglial phenotypes in unprecedented detail, and have highlighted robust changes in the expression of genes involved in lipid and lipoprotein metabolism. Increased expression of genes such as Apolipoprotein E (ApoE), Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) and Lipoprotein Lipase (LPL) in microglia during development, damage, and disease, suggest that increased lipid metabolism is needed to fuel protective cellular functions such as phagocytosis. This review describes our current understanding of lipid and lipoprotein metabolism in microglia, and highlights microglial lipid metabolism as a modifiable target for the treatment of neurodegenerative diseases such as Alzheimer's disease and multiple sclerosis.

Hedonic Eating and the "Delicious Circle": From Lipid-Derived Mediators to Brain Dopamine and Back

Palatable food can be seductive and hedonic eating can become irresistible beyond hunger and negative consequences. This is witnessed by the subtle equilibrium between eating to provide energy intake for homeostatic functions, and reward-induced overeating. In recent years, considerable efforts have been devoted to study neural circuits, and to identify potential factors responsible for the derangement of homeostatic eating toward hedonic eating and addiction-like feeding behavior. Here, we examined recent literature on “old” and “new” players accountable for reward-induced overeating and possible liability to eating addiction. Thus, the role of midbrain dopamine is positioned at the intersection between selected hormonal signals involved in food reward information processing (namely, leptin, ghrelin, and insulin), and lipid-derived neural mediators such as endocannabinoids. The impact of high fat palatable food and dietary lipids on endocannabinoid formation is reviewed in its pathogenetic potential for the derangement of feeding homeostasis. Next, endocannabinoid signaling that regulates synaptic plasticity is discussed as a key mechanism acting both at hypothalamic and mesolimbic circuits, and affecting both dopamine function and interplay between leptin and ghrelin signaling. Outside the canonical hypothalamic feeding circuits involved in energy homeostasis and the notion of “feeding center,” we focused on lateral hypothalamus as neural substrate able to confront food-associated homeostatic information with food salience, motivation to eat, reward-seeking, and development of compulsive eating. Thus, the lateral hypothalamus-ventral tegmental area-nucleus accumbens neural circuitry is reexamined in order to interrogate the functional interplay between ghrelin, dopamine, orexin, and endocannabinoid signaling. We suggested a pivotal role for endocannabinoids in food reward processing within the lateral hypothalamus, and for orexin neurons to integrate endocrine signals with food reinforcement and hedonic eating. In addition, the role played by different stressors in the reinstatement of preference for palatable food and food-seeking behavior is also considered in the light of endocannabinoid production, activation of orexin receptors and disinhibition of dopamine neurons. Finally, type-1 cannabinoid receptor-dependent inhibition of GABA-ergic release and relapse to reward-associated stimuli is linked to ghrelin and orexin signaling in the lateral hypothalamus-ventral tegmental area-nucleus accumbens network to highlight its pathological potential for food addiction-like behavior.

Lifestyle Shapes the Dialogue between Environment, Microglia, and Adult Neurogenesis

Lifestyle modulates brain function. Diet, stress levels, and physical exercise among other factors influence the "brain cognitive reserve", that is, the capacity of the brain to maintain a normal function when confronting neurodegenerative diseases, injury, and/or aging. This cognitive reserve relays on several cellular and molecular elements that contribute to brain plasticity allowing adaptive responses to cognitive demands, and one of its key components is the hippocampal neurogenic reserve. Hippocampal neural stem cells give rise to new neurons that integrate into the local circuitry and contribute to hippocampal functions such as memory and learning. Importantly, adult hippocampal neurogenesis is well-known to be modulated by the demands of the environment and lifestyle factors. Diet, stress, and physical exercise directly act on neural stem cells and/or their progeny, but, in addition, they may also indirectly affect neurogenesis by acting on microglia. Microglia, the guardians of the brain, rapidly sense changes in the brain milieu, and it has been recently shown that their function is affected by lifestyle factors. However, few studies have analyzed the modulatory effect of microglia on adult neurogenesis in these conditions. Here, we review the current knowledge about the dialogue maintained between microglia and the hippocampal neurogenic cascade. Understanding how the communication between microglia and hippocampal neurogenesis is affected by lifestyle choices is crucial to maintain the brain cognitive reserve and prevent the maladaptive responses that emerge during disease or injury through adulthood and aging.

Immunotherapies in Alzheimer's disease: Too much, too little, too late or off-target?

Years of research have highlighted the importance of the immune system in Alzheimer's disease (AD), a system that, if manipulated during strategic time windows, could potentially be tackled to treat this disorder. However, to minimize adverse effects, it is essential to first grasp which exact aspect of it may be targeted. Several clues have been collected over the years regarding specific immune players strongly modulated during different stages of AD progression. However, the inherent complexity of the immune system as well as conflicting data make it quite challenging to pinpoint a specific immune target in AD. In this review, we discuss immune-related abnormalities observed in the periphery as well as in the brain of AD patients, in relation to known risk factors of AD such as genetics, type-2 diabetes or obesity, aging, physical inactivity and hypertension. Although not investigated yet in clinical trials, C5 complement system component, CD40/CD40L interactions and the CXCR2 pathway are altered in AD patients and may represent potential therapeutic targets. Immunotherapies tested in a clinical context, those aiming to attenuate the innate immune response and those used to facilitate the removal of pathological proteins, are further discussed to try and understand the causes of the limited success reached. The prevailing eagerness to move basic research data to clinic should not overshadow the fact that a careful preclinical characterization of a drug is still required to ultimately improve the chance of clinical success. Finally, specific elements to consider prior to initiate large-scale trials are highlighted and include the replication of preclinical data, the use of small-scale human studies, the sub-typing of AD patients and the determination of pharmacokinetic and pharmacodynamics parameters such as brain bioavailability and target engagement.